Heart rate data collection

Abstract

One innovative aspect is directed to heart rate data collection. In some implementations, a circuit includes a light detector for generating a first electrical signal based on received light. The circuit includes a switching circuit, having a first and a second configuration, configured to receive a first voltage signal based on the first electrical signal and to switch among the first and the second configurations. The circuit includes first and second sampling circuits for sampling a value of the first voltage signal when the switching circuit is in the first configuration and second configurations, respectively. The circuit includes an ambient light cancellation circuit for generating a current signal to counter a first component of the first electrical signal when the first switching circuit is in the first configuration.

What is claimed is: 
     
       1. A device, comprising:
 a controller, the controller configured to, responsive to receiving a request to initiate a capture process, cause a first gain to be set in a first amplifier at a first time and to cause a light emitter control signal to be generated, wherein the light emitter control signal is configured to cause a light emitter to emit light towards a target surface; 
 a first sampling circuit comprising a second amplifier and configured to capture, while the first gain remains set and using the first amplifier and the second amplifier, at least one sample of a detected incident light signal received by the first sampling circuit while the light emitter control signal is generated to produce an analog representation of the detected incident light signal; and 
 an analog-to-digital converter configured to convert the analog representation of the detected incident light signal into a digital representation for further processing by the controller, wherein the controller is further configured to cause the light emitter control signal to stop and the first sampling circuit to be disabled substantially simultaneously with causing the analog-to-digital converter to convert the analog representation of the detected incident light signal into the digital representation. 
 
     
     
       2. The device of  claim 1 , wherein the digital representation is representative of a heartbeat of a user of the device. 
     
     
       3. The device of  claim 1 , wherein the controller is further configured to set a gain associated with an ambient light detection process. 
     
     
       4. The device of  claim 3 , further comprising:
 a light detector configured to detect ambient light and generate an ambient light signal responsive to such ambient light detection; and 
 at least a second sampling circuit configured to sample the ambient light signal and produce, at least partially based on the gain of the ambient light detection process, an analog representation of the ambient light signal for use in canceling an ambient component of the analog representation of the detected light signal. 
 
     
     
       5. The device of  claim 1 , wherein the controller is further configured to:
 disable, during the capture process, a zeroing of a light detector prior to causing the light emitter control signal to be generated. 
 
     
     
       6. The device of  claim 5 , wherein the controller is further configured to:
 enable the zeroing of the light detector after causing the generation of the light emitter control signal to stop. 
 
     
     
       7. The device of  claim 1 , wherein the controller is further configured to:
 cause a light emitter reset signal to be generated, reset the at least the first sampling circuit, and reset the at least the first amplifier after the capture process is completed in preparation for a further request to perform the capture process. 
 
     
     
       8. The device of  claim 4 , wherein the second sampling circuit is configured to:
 adjust or select an impedance based on the gain of the ambient light detection process; and 
 generate a gain adjustment signal to adjust a gain of the analog representation of the ambient light signal based on the gain of the ambient light detection process. 
 
     
     
       9. The device of  claim 1 , wherein the controller is further configured to set the first gain of the first amplifier based at least in part on historical data received by the controller. 
     
     
       10. The device of  claim 4 , wherein the second sampling circuit is configured to set the gain of the ambient light detection process based at least in part on historical ambient light data received by the controller. 
     
     
       11. A device, comprising:
 an input device configured to receive an input and generate, responsive thereto, a signal indicating a request to perform a capture process; and 
 a controller, communicatively connected with the input device and configured to:
 receive the signal from the input device; 
 set, responsive to receiving the signal, a first gain of at least a first amplifier at a first time; 
 cause, after setting the first gain, a light emitter of the device to emit a light signal; 
 cause a first sampling circuit, the first sampling circuit including a second amplifier, to capture, while the first gain remains set, at least one sample of a detected incident light signal routed through the first amplifier and the second amplifier to produce an analog representation of the detected incident light signal; 
 cause an analog-to-digital converter to convert the analog representation of the detected incident light signal into a digital representation for further processing by the controller; and 
 cause the light emitter and the first sampling circuit to be disabled substantially simultaneously with causing the conversion of the analog representation of the detected incident light signal into the digital representation by the analog-to-digital converter. 
 
 
     
     
       12. The device of  claim 11 , wherein the detected incident light signal is a light signal obtained from a target. 
     
     
       13. The device of  claim 11 , wherein the controller is further configured to:
 set a gain of an ambient light detection process; 
 cause a light detector to detect an ambient light signal; and 
 sample the ambient light signal at least partially based on the gain of the ambient light detection process to produce an analog representation of the ambient light signal. 
 
     
     
       14. The device of  claim 13 , further comprising an ambient light cancellation circuit configured to counter a component of the analog representation of the detected incident light signal attributable to ambient light using the analog representation of the ambient light signal. 
     
     
       15. The device of  claim 14 , wherein the controller is configured to operate the analog-to-digital converter after a first delay period, the first delay period selected to allow the component of the detected incident light signal attributable to ambient light to be countered by the analog representation of the ambient light signal. 
     
     
       16. The device of  claim 14 , wherein the controller is configured to operate the analog-to-digital converter after a first delay period, the first delay period selected to allow the analog-to-digital converter to settle to a known state. 
     
     
       17. The device of  claim 11 , wherein the controller is further configured to disable, as part of the capture process, a zeroing of a light detector prior to causing the light emitter to emit the light signal. 
     
     
       18. The device of  claim 17 , wherein the controller is further configured to enable the zeroing of the light detector after the disabling of the light emitter. 
     
     
       19. The device of  claim 11 , wherein the controller is further configured to reset the light emitter and the first sampling circuit in preparation for a further request to perform a sampling process. 
     
     
       20. The device of  claim 13 , further comprising a second sampling circuit configured to:
 sample the ambient light signal, 
 adjust or select an impedance based on the gain of the ambient light detection process; and 
 generate a gain adjustment signal based on the gain of the ambient light detection process to adjust a gain of the analog representation of the ambient light signal. 
 
     
     
       21. The device of  claim 11 , wherein the controller is further configured to set the first gain of the first amplifier based at least in part on historical data received by the controller. 
     
     
       22. The device of  claim 13 , wherein the second sampling circuit is configured to set the gain of the ambient light detection process based at least in part on historical ambient light data received by the controller. 
     
     
       23. The device of  claim 11 , wherein the digital representation is representative of a detected heartbeat of a user.